Until his resignation two months ago, the 62-year-old Mr Kalla served alongside Mr Susilo in President Megawati Sukarnoputri's cabinet. As one of three co-ordinating ministers, Mr Kalla had overall responsibility for eight major government departments including education, environment, labour and religion.

Ulil Abshar Abdalla, the head of the Liberal Muslim Network, is particularly positive: 'Yusuf was also one of Megawati's most decisive and effective cabinet ministers.

'At the same time, he has many friends and allies among the various Muslim associations and groups.'

Rizal Mallarangeng, director of the Freedom Institute, explains further: 'Mr Susilo and Yusuf have worked together closely and are a good team. They complement one another. While Mr Susilo is very Javanese - understated and a little cautious - Yusuf, as a Buginese, is more direct and to the point. He is also a quintessential problem-solver.

'For example he was willing to use his political capital to intervene personally and broker a peace in the strife-torn districts of Poso and Maluku. He's a man who gets things done.'

Mr Kalla is one of the country's richest men, and owns a large logistics and transportation business that includes a fleet of cargo ships, trucks and aeroplanes. He also controls the lucrative Toyota agency for eastern Indonesia.

In this respect, Mr Susilo has plumped for professionalism over electoral politics. By comparison, both his main competitors, Ms Megawati and former armed forces chief Wiranto, have chosen clerics from the 33-million strong Islamic association, the Nahdatul Ullama, as their running mates.

But while the two men are potential vote-winners, neither has served in government.

As such, Mr Kalla's selection is a welcome injection of pragmatism and sorely needed managerial skill into the country's woefully ramshackle administration.

Mr Kalla's tough, straight-talking manner is also important because it tempers Mr Susilo's own diffidence and tendency to indecision. Indeed, one of Ms Megawati's most noticeable weaknesses has been her unwillingness to reach out to the media and communicate her government's message. Her silences and indecision in times of crisis have been debilitating for her cabinet.

Mr Kalla is entirely different: 'I'd keep the lines open all the time,' he says. 'I would endeavour to make fast decisions and then explain to the people what we've done and what remains to be done.'

Moreover, the strong degree of familiarity and trust between Mr Susilo and his running mate means that a Kalla vice-presidency would be a very powerful position, allowing Mr Susilo to concentrate on security and political challenges while his No2 focuses on economics and business.

Felia Salim, an activist with a non-governmental organisation, says: 'Pak Yusuf ... knows how to implement policies. With his solid reputation in the business community, he's easily the most capable of all the candidates.'

Given the immense amount of public support evidenced, it is clear that many Indonesians crave the quiet diligence that the Buginese businessman embodies.

Karim Raslan is a lawyer and writer based in Kuala Lumpur